The background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art. Priority documents and publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply
CO2 capture from various flue gases is well known in the art, and numerous solvents are suitable for such capture. Most typically, chemical solvents, and especially amine-based solvents have become routine reagents. Unfortunately, amine-based solvents are susceptible to reacting with oxygen in the presence of metal ions, and particularly iron, and metal catalyzed degradation of the amine-based solvents is commonly observed. While not fully understood, it is generally believed that the iron involved in solvent degradation is derived from the carbon steel materials used in the construction of the CO2 removal equipment, possibly via complex formation with various amine compounds. To reduce such corrosion, inhibitors can be added to the solvent, and particularly well-known corrosion inhibitors include copper inhibitors.
Unfortunately, it has been found more recently that even though copper is a corrosion inhibitor, copper may also promote solvent degradation and formation of degradation products that may lead to severe corrosion of the CO2 removal equipment. As an alternative to using copper inhibitors, CO2 removal equipment may be constructed from stainless steel. However, most stainless steel construction is very expensive and thus generally disfavored. Nevertheless, in at least one instance, the inventors are aware of an installation where CO2 removal equipment had been constructed from stainless steel to avoid potential issues associated with iron leaching from carbon steel materials. Moreover, and because of the use of stainless steel, that installation also avoided use of copper inhibitors to so prevent any possibility of metal-catalyzed solvent degradation and corrosion of equipment. Quite unexpectedly, however, the stainless steel equipment was subject to corrosion.
Thus, there is still a need to provide systems, compositions, and methods to reduce or even eliminate corrosion of stainless steel components in CO2 removal systems, particularly where such systems are operated in the absence of copper inhibitors.